Various devices have been developed and used for producing "dams" or "dikes" at spaced intervals between crop rows to catch and retain water. These units have appropriately been named "dammers" or "dikers". They typically make use of rotating scraper blades pulled behind a tractor. A "dammer" typically makes use of blades mounted to a rotatable shaft pulled behind the tractor. The blade will scrape along the ground surface until a hill of soil builds up along the front blade surface. Then a tripping mechanism operates to allow the blade to rotate on the shaft, leaving the soil "dam" behind and lowering a successive blade into engagement with the ground to form the next "dam". Various tripping mechanisms and blade configurations have been developed for this purpose. Examples of various "dammers" or "dikers" are illustrated by the following United States patents:
U.S. Pat. No. 2,233,331 to Vratil, PA1 U.S. Pat. No. 2,236,832 to Nielsen, PA1 U.S. Pat. No. 2,780,975 to Gunning, PA1 U.S. Pat. No. 4,213,502 to Gibson, PA1 U.S. Pat. No. 2,098,738 to Campbell, PA1 U.S. Pat. No. 2,187,262 to Brown, PA1 U.S. Pat. No. 2,193,275 to Elliot, PA1 U.S. Pat. No. 2,196,038 to Silver.
Of the above patents, all deal with implements wherein soil "dams" are formed in furrows behind a furrow forming plowshare or cultivator. The top of the "dam" is typically at or near the original ground surface elevation with the furrow situated between the "dams".
Another form of water retention implement is commonly referred to as a "pitter". A "pitter" differs from a "dammer" or "diker" in function but not in principal. A pitter makes use of an extremely heavy frame carrying freely rotatable wheels with angular pitter blades spaced about their peripheries. The wheels roll freely over the ground when the tool is pulled ahead by a tractor. The shear weight of the frame and wheels drives the blades into the ground to form "pits" at spaced intervals. Such a "pitter" is produced by Milestone, Inc., Blackfoot, Idaho. The Milestone pitter includes inclined blades that enter the ground nearly vertically and exit nearly horizontally to form deep, wide pits. Individual bladed wheels are pivoted on a tool bar so each wheel can pivot elevationally relative to the others on the tool bar. The weight of the individual wheel and pivot frames are relied upon to drive the blades into the ground surface. Overall weight of the tool is therefore necessarily high.
A common problem facing those who use dammers or pitters is the rough "washboard" ground surface they leave along the ground. This roughened surface is later encountered by harvesters. The constant bouncing of harvester equipment as it moves over the rough terrain, often causes breakage of equipment and resultant time consuming repairs. Repair at harvest time is especially undesirable due to the need for harvesting the crop before any spoilage or over-ripening can occur. This is especially true in row crops in which dammers and pitters are most appropriately used. Nonetheless, the above forms of implements do contribute to conservation of moisture and reduction of runoff.
It remains desirable, though, to minimize the complexity and weight of such units and, further, to improve the operation thereof by forming a combination of pits and dams that will more effectively retain water and resist runoff, while minimizing "washboarding" of the ground surface.